The present invention relates to improving wet finger tracking on a capacitive touchscreen, and more specifically, to methods to analyze patterns of touch on a touchscreen for the presence of liquid and interpret subsequent touches to improve performance on the touch screen.
A touchscreen is an electronic display sensing the location of a touch event within the display area. The touching may be done with a finger, but can also be done with passive objects such as a stylus. Touchscreens may be used in devices such as all-in-one computers, tablet computers, and smartphones. There are a variety of touchscreen technologies, such as resistive, capacitive, infrared, and the like.
Capacitive sensing is one of the more commonly used technologies for touchscreens. A capacitive touchscreen includes an insulator such as glass, coated with a transparent conductor, e.g. indium tin oxide. Touching the surface of the screen with a conductive object results in a distortion of the electrostatic field of the screen. The distortion of the electrostatic field on the screen can be measured by a change in capacitance.
A problem with capacitive sensing technologies in touchscreens is that the capacitive touchscreen cannot decipher between an active touch and false touch. For example, when water on the surface of the touchscreen registers as a touch because water is a conductive object. Subsequent attempts to use the touchscreen may be ignored or cause unpredictable multi-touch sequences. As touchscreens are being used in more locations and on more rugged devices, the presence of liquid on a touchscreen is becoming an increasingly important problem to solve.